Interferometric measuring devices of this type, usually described as white light interferometers, are known in various embodiments, for which reference may be made, for example, to German Patent Application Nos. DE 100 47 495, DE 101 31 780, DE 100 39 239 and DE 101 31 779, including the additional publications cited in these documents. All of these interferometric measuring devices have in common that for the depth scanning of the surface the object light path is adjusted in relation to the reference light path by a unit moving the object, the optical scanning device, or the reference surface in the depth scanning direction (z-direction). It is known that interference phenomena occur only within the coherence length of the light emitted by the light source, which is, for example, in the range of a few micrometers. The shape of the surface is measured, for example, by determining the maximum interference using the evaluation device; however, other evaluation criteria are also conceivable. In order to obtain precise results, the actuating unit designed as an actuating mechanism or a piezoelectrically operated unit must, in particular, be precisely adjusted and made insensitive to external influences such as those occurring in a manufacturing process, in particular.
An object of the present invention is to provide an interferometric measuring device of the type defined above, which provides depth scanning which is as insensitive as possible.